I keep getting “Dimensional analysis” questions wrong in Units, Dimensions & Measurement. What's the trap?
thinking a dimensionally-correct equation must be numerically correct — dimensionless constants (like 2 or π) are invisible to it.
The usual trap: thinking a dimensionally-correct equation must be numerically correct — dimensionless constants (like 2 or π) are invisible to it. How to avoid it: use it as a quick error-check and to convert units, not to fix constants. Go back to the definition — expressing every quantity in powers of mass (M), length (L) and time (T) so you can check or derive relations.
Key point
Dimensional analysis
Common mistake
thinking a dimensionally-correct equation must be numerically correct — dimensionless constants (like 2 or π) are invisible to it.
Memory tip
use it as a quick error-check and to convert units, not to fix constants.
Tap to watch or see it right here — the app stays open (it only opens a quick search if nothing embeddable is found).